The Coen brothers' cat and mouse chase in the sweet land of liberty

On the face of it, "No Country for Old Men" doesn't need to be set in 1980. A stunningly assured piece of moviemaking from the Coen brothers - perhaps their weightiest yet most cleanly crafted work to date - the film unfolds in the parched landscapes and small towns of the American Southwest. It could be taking place anytime in the past 40 years, really.

By locating the action in the year of Ronald Reagan's ascension to the presidency, though, "No Country" stands at the pivot of the Old West and the New Avarice, a point in time when the last vestiges of frontier morality have been washed away by a pitiless modern crime wave fueled by drug profits.

Standing in for the old ways is Terrell County Sheriff Ed Tom Bell, whom Tommy Lee Jones plays with the uncertain majesty of a biblical patriarch. The lines on the actor's face have never looked more harshly carved: Something's eating Ed Tom from the inside, and for the longest time he can't put words to it. "I think once you stop hearing 'Sir' and 'Ma'am,' all the rest follows," is about the closest he can come.

But "No Country for Old Men" isn't about him. Adapted from Cormac McCarthy's 2005 novel, the film is a cat-and-mouse drama that unfolds on an epic stage, and that without ever straining suggests the sea change that has turned America into a dark twin of its early promise. The Coens are working with the same mixture of fate, circumstance, and criminality as in "Blood Simple" and "Fargo," but everything about this movie feels bigger, more mature.

The mouse is Llewellyn Moss (Josh Brolin), a blue-collar welder and weekend hunter who happens upon the aftermath of a drug deal gone sour in the Texas borderlands. The scene's a surreal tableau of carnage: gut-shot guard dogs, pickup trucks and men full of holes. The sole survivor faintly asks for water in Spanish; another man lies dead under a nearby tree with $2 million in a bag at his feet. Llewellyn takes the money and, later that night, spurred by a vague sense of guilt, returns with a jug of water. He tells his wife (Kelly Macdonald) that he's "fixin' to do somethin' dumber than hell," and for once he's right.

Enter cat: a bounty hunter named Anton Chigurh (Javier Bardem), who's employed by the upper echelon drug-men to retrieve their cash. If Sheriff Ed Tom is the descendant of old-school Western lawmen and Llewellyn seems to come from a line of terse, capable pioneers (he lives in a trailer park, as if that's where the wagon train came to ground), Chigurh is like nothing before seen on this earth.

Bardem plays this hired assassin with a creepy page-boy haircut and the eyes of a religious fanatic. "He's a peculiar man," says another character. "Might even say he has his principles." Indeed: as in the novel, Chigurh is given to dreamy philosophical soliloquies that transfix his victims like hypnotized sparrows. If his words are impenetrable - a madman's serene logic - his choice of weapon isn't: a hissing slaughterhouse air-gun that punches a hole in a man's head before he knows what hit him.

"No Country for Old Men" is consequently awash with blood and mayhem, but it's hardly an action movie. As Chigurh trails Llewellyn on a zigzag chase through the lesser motels of the US-Mexican border area, and as Ed Tom and his deputy (Garret Dillahunt) try desperately to catch up, the Coens keep their distance. The film is exciting yet strangely quiet, attuned to the play of cloud-shadow and moonlight on vast landscapes and to the tiny struggles of men within them. The ghost of our history looms behind everything here except the assassin, who's something horribly new and who demands we call our fate on the flip of a coin.

McCarthy's prose can be spare to the point of Hemingway-esque self-parody, and if "No Country" isn't his best work, it allows the filmmakers and actors the freedom to do a lot more with less. Flashes of Coen brothers wit have been inserted into the proceedings: a drug runner's dog that comes after Llewellyn like a riverbound hellhound, Woody Harrelson swaggering with juicy egotism as a killer hired to kill the killer. By contrast, Macdonald - a Scottish actress ("Gosford Park") making her US movie debut - is heartbreakingly true to the book as a small-town wife caught up in a cataclysm she can see coming miles off.

The Coens also understand the stark immediacy of this tale, and they visualize it with brilliantly judged details: the hole in a dead man's shoe, a row of fan belts arrayed like hangmen's nooses behind a gas station attendant's head. In one scene, Llewellyn and Chigurh move through empty nighttime streets, and even the sound-mix is right: the high metallic whine of a far-off Interstate.

The brothers don't make movies "about" something, though, and they never have. They tell stories and they let you do the math. So it is here. Yet the climactic scenes of their "No Country" have a greater heft - a fuller sense of Old Testament summation - than McCarthy's, whose final chapters gave way to drift.

Both book and movie offer glimpses of a huge, mysterious pattern that we and the characters can't quite see - that only God could see, if He hadn't given up and gone home. (There's barely any soundtrack music in the entire movie; the angels have packed up, too.) In the end, the film's central image is Ed Tom's expression of bottomless sorrow. It's the grief of a man for a land his fathers tamed and in which he now walks as a stranger.